The present invention relates to a hydraulic press for forming metal plates.
Japanese laid-open patent publication number 63-49410 discloses a similar machine for performing compression forming of plastic. In that device, a plurality of pressure cylinders (hydraulic cylinders) are used to raise and lower a movable plate. Since a single piston is used to both raise and lower the movable plate, a large amount of pressurized oil is required.
Japanese laid-open patent publication number 01-266999 and Japanese laid-open patent publication number 02-84308 disclose conventional technologies for controlling the degree of horizontal uniformity of the movable plate. In these technologies, a bed or a bolster is equipped with a hydraulic cylinder to serve as a countering mechanism. The degree of horizontal uniformity is maintained by having the bed or bolster press against the lower surface of the movable plate when it is close to the bottom dead center point. However, these types of hydraulic cylinders that act as countering mechanisms can be an obstruction when replacing dies and the like, and there is also a shock when the lower surface of the movable plate comes into contact with the countering hydraulic cylinder.
Referring to FIGS. 9(a)-9(e), there is shown the steps involved in the conventional technology for pressing an outer panel that serves as a section of the vehicle body of an automobile. This invention relates to a new apparatus geared at performing those steps in a better way.
The steps for transforming blank B into an outer panel are:
a. A blanking operation results in blank B by cutting or shearing a coiled material. PA1 b. Blank B is drawn using upper and lower dies. PA1 c. Upper and lower dies are used to trim the outer perimeter and a piercing punch is used to form an opening in a section of the workpiece. PA1 d. Upper and lower dies are used to form a flange on the outer perimeter. PA1 e. A cam die is used to apply pressure in the direction shown by the arrows and to form a flange.
Steps 9(a)-9(e) are conventionally performed in separate operations requiring moving the workpiece from one machine to another.